A Chinese Mathematician Reveals How to Beat Anyone at Rock-Paper-Scissors

Rock-paper-scissors has been around for thousands of years. The seemingly simple hand game proves useful in randomly selecting a winning and losing player using very basic rules: rock smashes scissors, scissors cuts paper, paper covers rock.

However, the game is not as simple as many think. Rather than just a game of chance, rock-paper-scissors can be played strategically using math, skill and psychology.

The Mathematical Approach

Game theory researchers at the University of Hangzhou in China studied the game and how players decide what to throw when playing.

They conducted an experiment that drafted 360 students from Zhejiang University in Hangzhou to play rock-paper-scissors for hours with each other. The pairs played a total of 300 rounds per game. Researchers recorded each decision made per game. This helped them identify patterns of how players reacted while playing the game.

The findings showed that players tend to repeat strategies that are successful (if it worked once, it’s going to work again) and change those which aren’t. This repetition is also called “conditional response.”

From this data we can strategize playing this way:

1) If you played scissors and your opponent played rock, for instance, there is a very high chance that your opponent will play rock again since it already won. This means that playing paper in the next round gives you a higher probability of winning.

2) If your opponent’s throw loses, copy their losing throw for the next round because your opponent will figure you won’t use something that previously lost.

These recommendations are based on the pattern found in the study of winners repeating their strategy and losers moving to the next strategy in a sequence.

The Behavioral Approach

Expert players watch and study their opponents to gain the upper hand when playing. While the first approach was a result of measuring repeated actions, this next technique exploits players’ behaviors in different conditions and settings. By learning more about your opponent, you will be better at playing against them.

1) Watch your opponent play other players. Do they play in a pattern similar to the math approach? Do they have a unique strategy or are they random, leaving you second-guessing?

2) According to experienced players, newbie players have their own tendencies: males tend to lead with rock. So if you are to play a one-shot game with a guy, it’s best to lead with paper. Women, on the other hand, tend to start with scissors. So if you’re playing a female rookie player, lead with rock.

3) As a general rule, if someone makes the same throw twice, they will not want to make it again the third time. Example: if someone throws paper twice, they’ll probably throw either rock or scissors next time. Using rock will now give you an advantage as you can just either win or draw.

If you really want to master rock-paper-scissors, practice is key. With the information above, you can become a roshambo master in no time.

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